This invention relates generally to pumps for groundwater sampling and the like, and, more particularly, to automated air-operated pumps with removable cartridges and improved manifold attachment mechanisms.
There does exist many types of submersible pumps for groundwater sampling and other uses. FIG. 1 shows, generally at 10, a typical prior-art configuration. Since devices of this kind are inserted down well holes, the unit consists of an outer cylindrical pump body 2, typically constructed of stainless steel. The body includes a lower inlet end 4 and an upper outlet end 6. An internal cylindrical bladder 8, typically constructed of Teflon, partitions the interior of the pump body 2 into a gas-carrying section 11, and a fluid-carrying section 12 within the bladder 8.
A tube 14 having, perforations 16, is generally positioned within the fluid-carrying section 12, as shown. A lower check valve 20 is provided at the lower inlet end 4 to permit groundwater or like fluids to pass through the lower end 4 and into the tube 14 and fluid-carrying chamber 12 through perforations 16. The check valve 20 also prevents the fluid from backflowing through the lower inlet 4. An upper check valve 22 allows fluid from the fluid-carrying chamber 12 to be discharged through the upper end 6 by passing through apertures 16 and into the tube 14. The upper check valve 22 also prevents the fluid from backflowing down into the pump interior.
Above ground, a controller 30 is provided having a conduit 32 in pneumatic communication with the gas-carrying section 11 within the pump body 2. The apparatus operates by pressurizing and venting the gas within the chamber 11, thereby compressing and expanding the bladder 8, which is quite flexible, thereby forcing fluid within the chamber 12 out the upper end 6 through tube 14 by way of apertures 16. More particularly, when the pump body is submerged, ground water or other fluid flows into the chamber 12 through tube 14 having apertures 16 through the lower end 4, bypassing check valve 20 due to natural hydrostatic pressure.
When an actuating gas such as compressed air is driven through conduit 32 and into the gas-carrying section 11, the bladder 8 is compressed and the lower check valve 20 is forced against the opening 4, thereby forcing the fluid contained within the fluid-carrying section upwardly and out through the upper opening 6, displacing check valve 22 in its path. The gas-carrying chamber 11 is then vented at ground level through controller 30, permitting a fresh charge of ground water to again fill the fluid-carrying chamber 12 and tube 14 through perforations 16, at which time another cycle may be started by compressing the bladder 8.
Although a single controller 30 may be configured to control a multiplicity of similar pumps, the timing sequences for each pump must be optimized and stored to ensure the most efficient operation for each sampling station. The timing/cycling means within the controller therefore typically includes a 3-way valve associated with each pump to which it is connected. The 3-way valve is alternatively actuated and de-actuated to produce a pulsating flow to the bladder of each pump, wherein a compressed gas is applied via each conduit 32, on which the 3-way valve changes state, enabling the gas contained within chamber 11 to be vented to atmosphere. The controller 30 must therefore include electronic, pneumatic or mechanical timing devices associated with each 3-way valve, in each pump, to ensure proper operation thereof.
Pumps of the type just described are used in a variety of applications, including the continuous collection of gasoline and other hazardous materials from aquifers, as well as occasional groundwater sampling. There is also a need for pumps used for more infrequent sampling, using a device sometimes referred to as a xe2x80x9cbailor.xe2x80x9d Originally, such devices assumed the form of a polyethylene or Teflon tube having a bottom end with a check ball. The device was lowered into a well, allowing liquid to trickle past the check ball until the tube was filled and the check ball was seated. The device was then removed form the well, the sample removed, and the rest of the device discarded.
By EPA mandate, the bailing process must remove three times the volume of a well before a sample is taken. This means that if the volume of the well is 50 gallons, 150 bailing operations must be taken prior to taking the actual sample. The time-consuming nature of this process led to the development of continuously cycling sampling pumps of the type described with reference to FIG. 1. Even with these, however, the apparatus is expensive, and the bladder must be removed, typically requiring a meticulous dismantling of the pump body. The need therefore remains for an economical pump capable of repetitive sampling. Ideally, such a pump would include some form of collection cartridge that is easily removable, allowing the pump to be used for more infrequent sampling applications, including bailing.
This invention resides in an air-operated pump for groundwater sampling and other applications, including a removable cartridge coupled to a manifold configured to receive air-inlet and fluid-discharge tubes from an above-ground location. A submersible pump according to the invention includes a pump body having a fluid inlet port, an air-supply port and a fluid-discharge port. The removable cartridge is disposed within the pump body. The removable cartridge may be in the form of a bellows or bladder, and may be removably attachable to the manifold portion of the pump body through a press fitting.
As in previous designs, the cartridge is operable between a refill state, wherein fluid is drawn into the pump body through the fluid inlet port, and a discharge state wherein fluid is forced out of the pump body through the fluid-discharge port. In contrast to prior implementations, however, the pump body features a manifold with fittings enabling the air-inlet and fluid-discharge tubes to be respectively inserted and sealed into the air-inlet and fluid-discharge ports.
In the preferred embodiment, the fittings are such that the associated tubes cannot be removed without modification. For example, the fittings may include a grab plate associated with one or both of the air-inlet and fluid-discharge ports. Each grab plate includes an aperture with finned serrations such that through proper sizing of the plate features and associated tubing, the tube(s) may be inserted and sealed through appropriate compression. Such compression may be provided through the construction of an upper cover, preferably provided with a two-stage bayonet mount, or the fittings may include a compression adapter with one or more sets of O-rings associated with one or both of the air-inlet and fluid-discharge ports.